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A comparison of self-ligating and conventional orthodontic bracket systems
G E Read-Ward1, S P Jones, E H Davies
1Department of Orthodontics, Royal Bournemouth Hospital, U.K.
British Journal of Orthodontics
|February 12, 1998
Summary
Self-ligating brackets generally show less friction than conventional steel-ligated brackets. However, factors like wire size and angulation significantly impact frictional resistance for all bracket types.
Area of Science:
- Orthodontics
- Biomaterials Science
Background:
- Frictional resistance is a critical factor in orthodontic bracket performance.
- Self-ligating brackets aim to reduce friction compared to conventional ligation methods.
Purpose of the Study:
- To compare the static frictional resistance of three self-ligating brackets against a conventional steel-ligated bracket.
- To evaluate the influence of archwire size, bracket/archwire angulation, and saliva on frictional resistance.
Main Methods:
- Ex-vivo comparison of frictional resistance.
- Tested three self-ligating brackets (Mobil-Lock Variable-Slot, Activa, SPEED) and one conventional bracket (Ultratrimm).
- Varied archwire sizes (0.020, 0.019x0.025, 0.021x0.025 inches), angulation (0, 5, 10 degrees), and presence of saliva.
Main Results:
- Increased wire size and angulation consistently increased frictional resistance for all brackets.
- Mobil-Lock showed least friction at 0-degree angulation; Activa was second lowest.
- Friction increased significantly for SPEED with rectangular wires or angulation.
- Ultratrimm exhibited high variability, indicating inconsistent ligation force.
Conclusions:
- Self-ligating brackets demonstrated reduced friction compared to steel-ligated brackets only under specific conditions.
- Bracket type, wire dimensions, and angulation are crucial determinants of frictional forces in orthodontic treatment.